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If photons were not purely massless, their speeds would vary with frequency, with lower-energy (redder) photons moving slightly slower than higher-energy photons. Relativity would be unaffected by this; the so-called speed of light, c , would then not be the actual speed at which light moves, but a constant of nature which is the upper bound on ...
For the remainder of the photon epoch, the universe contained a hot dense plasma of nuclei, electrons and photons. [2] At the start of this period, many photons had sufficient energy to photodissociate deuterium, so those atomic nuclei that formed were quickly separated back into protons and neutrons. By the ten second mark, ever fewer high ...
1932 Antielectron (or positron), the first antiparticle, discovered by Carl D. Anderson [13] (proposed by Paul Dirac in 1927 and by Ettore Majorana in 1928) : 1937 Muon (or mu lepton) discovered by Seth Neddermeyer, Carl D. Anderson, J.C. Street, and E.C. Stevenson, using cloud chamber measurements of cosmic rays [14] (it was mistaken for the pion until 1947 [15])
15 January – Researchers in China report the successful transmission of entangled photons between drones, used as nodes for the development of mobile quantum networks or flexible network extensions, marking the first work in which entangled particles were sent between two moving devices. [329] [330]
1964 - First black hole, Cygnus X-1, discovered; 1964 – CP violation discovered by James Cronin and Val Fitch. 1965 – Arno Penzias and Robert Wilson: Cosmic Microwave Background (CMB) discovered; 1967 – Unification of weak interaction and electromagnetism (electroweak theory) 1967 – Solar neutrino problem found
1897 J. J. Thomson discovered the electron; 1897 Emil Wiechert, Walter Kaufmann and J.J. Thomson discover the electron; 1898 Marie and Pierre Curie discovered the existence of the radioactive elements radium and polonium in their research of pitchblende; 1898 William Ramsay and Morris Travers discover neon, and negatively charged beta particles
With frequencies above 30 exahertz (3 × 10 19 Hz) and wavelengths less than 10 picometers (1 × 10 −11 m), gamma ray photons have the highest photon energy of any form of electromagnetic radiation. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium.
5th century BC – Democritus proposes that the bright band in the night sky known as the Milky Way might consist of stars. 4th century BC – Aristotle believes the Milky Way to be caused by "the ignition of the fiery exhalation of some stars which were large, numerous and close together" and that the "ignition takes place in the upper part of the atmosphere, in the region of the world which ...